Method and system for multiple training sequences for peak-to-average power ratio reduction in precoded bursts

Abstract

A method and apparatus for peak to average power ratio reduction, the method precoding the data symbols using an inverse discrete Fourier transform (‘IDFT’), choosing, at a transmitter, a set of training sequence symbols from a plurality of sets of training sequence symbols, and creating, at the transmitter, an IDFT precoded burst by adding the IDFT of the data symbols and an IDFT of the chosen set of training sequence symbols. Further, a method and receiver, the method receiving a burst, performing a discrete Fourier transform on the burst, choosing a training sequence among a known plurality of training sequences sets, the chosen training sequence resulting in the least noise estimate among the plurality of training sequence sets, and demodulating the burst with the detected pilot burst.

The invention claimed is: 
     
       1. A method comprising:
 precoding data symbols using an inverse discrete Fourier transform (IDFT); 
 choosing, at a transmitter, a set of training sequence symbols from a plurality of sets of training sequence symbols; and 
 creating, at the transmitter, an IDFT precoded burst for transmission by adding the IDFT of the precoded data symbols and an IDFT of the chosen set of training sequence symbols. 
 
     
     
       2. The method of  claim 1 , further comprising calculating a peak to average power ratio for the IDFT precoded burst. 
     
     
       3. The method of  claim 2 , wherein the chosen set of training sequence symbols is picked such that the calculated peak to average power ratio for the IDFT precoded burst is the lowest amongst all of the plurality of sets of training sequence symbols or is less than or equal to a predetermined value. 
     
     
       4. The method of  claim 2 , wherein, after creating the IDFT precoded burst, said IDFT precoded burst is filtered using a transmit pulse shaping filter and before the peak to average power ratio calculation. 
     
     
       5. The method of  claim 4 , wherein, after the peak to average power ratio calculation, the method performs the choosing and creating steps for a new set of training sequence symbols if the peak to average power ratio value is greater than a predetermined value. 
     
     
       6. The method of  claim 1 , wherein each set within the plurality of sets of training sequence symbols is known to a receiver. 
     
     
       7. The method of  claim 1 , wherein, after creating the IDFT precoded burst, a cyclic prefix is appended to said IDFT precoded burst. 
     
     
       8. The method of  claim 7 , wherein each of the plurality of sets of training sequence symbols is IDFT precoded, added with a cyclic prefix, filtered and stored in a memory of the transmitter. 
     
     
       9. The method of  claim 1 , wherein the IDFT precoded data symbols are filtered by a transmit pulse shaping filter prior to the creating, and wherein the training sequence symbols are IDFT precoded and filtered by the same transmit pulse shaping filter prior to the creating. 
     
     
       10. The method of  claim 9 , wherein each of the plurality of sets of training sequence symbols is IDFT precoded, added with a cyclic prefix, filtered and stored in a memory of the transmitter. 
     
     
       11. The method of  claim 9 , wherein at least one of the plurality of sets of training sequence symbols is IDFT precoded, added with a cyclic prefix, filtered and stored in a memory of the transmitter and the remaining of the plurality of sets of training sequence symbols are obtained by operation on the at least one set of stored set of training sequence symbols. 
     
     
       12. The method of  claim 1 , wherein each of the plurality of sets of training sequence symbols is IDFT precoded and stored in a memory of the transmitter. 
     
     
       13. The method of  claim 1 , wherein at least one of the plurality of sets of training sequence symbols is IDFT precoded and stored in a memory of the transmitter and the remaining of the plurality of sets of training sequence symbols are obtained by operation on the at least one stored IDFT precoded set of training sequence symbols. 
     
     
       14. A communications subsystem in a mobile device, the communications subsystem comprising:
 a transmitter; 
 memory configured to store instructions; and 
 a processor configured to execute the instructions to:
 precede data symbols using an inverse discrete Fourier transform (IDFT); 
 choose, at the transmitter, a set of training sequence symbols from a plurality of sets of training sequence symbols; and 
 create, at the transmitter, an IDFT preceded burst for transmission by adding the IDFT of the precoded data symbols and an IDFT of the chosen set of training sequence symbols. 
 
 
     
     
       15. The communications subsystem of  claim 14 , wherein the processor configured to execute the instructions is further configured to calculate a peak to average power ratio for the IDFT precoded burst. 
     
     
       16. The communications subsystem of  claim 14 , wherein the processor configured to execute the instructions is further configured to filter the IDFT preceded data symbols by a transmit pulse shaping filter prior to the creating, and IDFT precede and filter the training sequence symbols by the same transmit pulse shaping filter prior to the creating. 
     
     
       17. The communications subsystem of  claim 14 , wherein the memory stores each of the plurality of sets of training sequence symbols after the IDFT preceding. 
     
     
       18. The communications subsystem of  claim 14 , wherein the memory stores an IDFT of at least one of the plurality of sets of training sequence symbols, and the processor configured to execute the instructions is further configured to obtain the remaining of the plurality of sets of training sequence symbols by mathematical operation on the stored IDFT of at least one of the plurality of sets of training sequence symbols. 
     
     
       19. A non-transitory computer-readable storage medium storing instructions that when executed by at least one processor, cause the at least one processor to perform operations of:
 precoding data symbols using an inverse discrete Fourier transform (IDFT); 
 choosing, at a transmitter, a set of training sequence symbols from a plurality of sets of training sequence symbols; and 
 creating, at the transmitter, an IDFT precoded burst for transmission by adding the IDFT of the precoded data symbols and an IDFT of the chosen set of training sequence symbols.